Electro-deposition of nickel coatings



United States Patent 3,006,822 ELECTRO-DEPOSITION 0F NICIGEL COATINGS Hans Guenther Todt, Berlin-Charlottenburg, Germany,

assignor, by mesne assignments, to Langbein Pfanhauser Werke, A.G.,.Neuss (Rhine), Germany, a corporation of Germany No Drawing. Filed May 8, 1957, Ser. No. 657,704 8 Claims. (Cl. 204-49) The present invention relates to the electric-deposition of high-luster nickel coatings, and more particularly to high-luster promoting agents used as additives in electrolytic nickel baths,

It is known to add high-luster promoting agents to conventional galvanic nickel baths, such as nickel sulfatenickel chloride, nickel sulfamate and nickel borofluoride baths, such known agents including sulfamines, aldehydes, thio compounds and unsaturated polyhydric alcohols, especially polyhydric alcohols containing a triple bond. However, the latter alcohols have a tendency to form condensation products which unfavorably influence the luster formation. Attempts have been made to overcome this disadvantage by the addition of certain aldehydes as condensation inhibitors.

However, while a great number of processes have become known to produce galvanic nickel coatings of high luster and while many luster-promoting organic compounds have been proposed as additives for the electrolytic nickel bath, the problem has not been solved to the full satisfaction of the industry. It ha been impossible, for instance, to predict on the basis of its chemical composition whether or not a certain substance would show luster promoting qualities.

It is the principal object of the present invention to produce galvanic nickel coatings with good mechanical properties and a high luster which may be so brilliant that the coating need not be polished if the base material is sufi'iciently smooth.

It is a concomitant object of this invention to provide a new class of luster-promoting additives for electrolytic nickel baths.

It is a specific object of the invention to provide as new compositions of matter a group of ionizing acetylene compounds useful as luster-promoting agents in electrolytic nickel baths.

I have found that ionizing unsaturated hydrocarbons containing a triple bond, either alone or especially in combination' with known thio compounds used for this purpose, possess outstanding luster-producing properties.

The ionizing hydrocarbons as a class do not only have excellent luster-promoting qualities but they also fulfill most other requirements of an industrially useful electrolytic bath additive. Thus, while other acetylene compounds also have luster-producing properties, most of them were found to be useless for the purpose because they are either too unstable, having a tendency to condensation and polymerization, or they evaporate too easily, or they are of insufficient solubility, or they are effective luster-promoting agents only in a very narrow current density range, or the luster they produce is not sufiicient. All these disadvantages are almost completely absent in the case of acetylene compounds which form ions in aqueous solution.

The ionizing acetylene derivatives of the present invention are very stable and show no tendency to condense or polymerize. They are readily soluble in water and are not volatile even at elevated temperatures, Electrolytes contaim'ng such additives are highly dependable in opera tion because .they neither form undesirable decomposition products nor is there an uncontrollable disappearance of the additive due topartial evaporation.

In addition, I have found that the ionizing acetylene compounds have special properties in regard to the luster formation of the deposited nickel coating. Whereas substances dissolved in the form of molecules can reach the cathode only by diffusion and the luster of the coating can, therefore, not satisfy all requirements from the point of View of uniformity at different current densities, the migration of luster-producing ions takes place under the influence of the electrolytic field so that a very good luster in depth is achieved. Optimum elfects can be attained by combining ions of dilferent diameters and/or diiferent electric charge.

Ionizing acetylene compounds containing ions of different electric charge in the molecule are also very suitable. These include, for example, quaternary ammonium compounds with aliphatic or aromatic radicals of which one or more are sulfurated. Such sulfurated quaternary ammonium compounds are substances of amphoteric nature and have a positive charge derived from nitrogen and one or more negative charges derived from the sulfo-group.

Examples of luster promoting electrolytic bath additives according to the invention include:

(1) Quaternary ammonium compounds with at least one triple bond in the molecule, namely compounds of the general formula in wherein R R and R are members selected from the group consisting of hydrogen, alkyl and aryl radicals, R is an alkyne radical, and X is a member selected from the group consisting of halogen and hydroxide, for example- Trimethyl-propargyl-ammonium chloride CH3 omit-0117435011 o1- CH3 Triethyl-propargyl-ammonium hydroxide HsCz-NIJHz-CECH OH- C2H5 Phenyl-dimethyl-propargyl-ammonium chloride CH3 HsCs-hT-CHr-OEOH o1- CH3 Propargyl-ammonium hydroxide H armour-050E on- H Ethinyl-ammonlum hydroxide H n-llrc=cn OH- (2) Aliphatic or aliphatic-aromatic, nitrogen-containing compounds with at least one carbon triple bond and one or more sulfo-groups, for example 619 t 0 Hz 0 E C H N -propargyl-pyridine-3- sultonic acid C H a (4) CHz-CECH N-methyl-N,N-dipropargylaminomethane sulionic acid These compounds may be used as sole luster-promoting nickel electrolytic bath additives in concentrations of 0.005 to 1 gram/liter, preferably 0.01-0.2 g./l. They also considerably improve the luster-promoting qualities of such baths containing conventional luster-producing additives.

I have found triethylpropargyl ammonium chloride to be the preferred additive among the ionizing acetylene compounds of this invention because of its exceptional uniformity of luster depth and its eifectiveness with'very high current densities. The latter effect is a result of its strong inhibitory action.

Many of the ionizing acetylene compounds are'new compositions of matter. Generally, they are produced by conventional methods, as follows:

The amine of the desired type (i.e. tiiethylamine,

. morpholine, etc.) is reacted in stoichiometric ratio with an unsaturated alcohol or halogenide containing a triple bond. The reaction begins at room temperature and is usually so violent that it must be effected in an inert solvent. If this solvent is so selected that the obtained ammonium salt is insoluble therein, the salt will be precipitated as it is formed and need only be separated.

The unsaturated ammonium compounds with a triple bond are readily water-soluble, frequently hygroscopic salts which usually have no definite melting point but decompose while assuming a brown discoloration and partially liquefying.

By way of example, the production of certain novel compositions is hereinafter described.

TRIMETHYLPROPARGYL AMMONIUM CHLORIDE A flask with three tubes, a reflux cooler, and agitator anda droppingrfunnel was used as reaction vessel. A mixture of 95.57 g. (1 mol) trimethylamine hydrochloride and 100 g. chloroform were put into the flask and 74.5 g. -(1 mol) of propargyl chloride was slowly dropped into the flask while the mixture was constantly agitated. The temperature rose to mild boiling. Whenever the reaction became too violent, the introduction of propargyl chloride was temporarily interrupted.

Trimethylpropargyl ammonium chloride was crystallized even dun'ngthe reaction. To complete the reaction, the mixture was left standing overnight, the reaction productwas filtered off and washed with a little chloroform. The washed filtrate was finally dried at about 80 C.

The raw product was yellowish to light brown and was purified by recrystallization with chloroform. The yield depended on the purity of the starting materials. When freshly distilled colorless propargyl chloride and pure trimethylamine hydrochloride was used, the yield was 90-10()% of theoretical. With brownish raw materials of less purity, the yield declines to 50-90%.

Pure trimethyl propargyl ammonium chloride forms colorless, hygroscopic crystals having a decomposition temperature of about 280 C. It is readily soluble in water, alcohol, glacial acetic acid, dimethylformamide and soluble in chloroform. It is insoluble in benzene, ether, trichloroethylene and tetrahydrofurane.

The same procedure may be followed While substitut- 1ng propargyl bromide or propargyl alcohol for propargyl chloride. In the first instance, trimethylpropargyl ammonium bromide is obtained while trimethyl propargyl ammonium hydroxideis obtained with the alcohol. In the latter case, the reaction must be continued to boiling. The reaction proceeds slower and the yield is about 50%.

TRIETHYLPROPARGYL AMMONIUM CHLORIDE This substance may be obtained by the same method as set forth hereinabove by replacing the trimethylamine hydrochloride with triethylamine. The reaction was effected with 101.19 g. (1 mol) triethylamine, 74.5 g. (l L SODIUM N-PROPARGYL-PYRIDINE-3 SULFONATE 10 A suspension of 181 g. (1 mol) of sodium pyridine-3 sulfonate in 750 cc. methyl alcohol was put into the same type of reaction vessel as hereinabove mentioned, and, while constantly agitating the mixture, 178.5 g. (1.5 mol) of propargyl bromide was slowly dropped into the flask.

The reaction mass was left standing overnight and the crystalline powder was filtered off and washed with a mixture of methyl alcohol and ether. The raw product was purified by dissolving it in a little water and precipitating the solution with alcohol.

The end product is a fine, reddish-brown crystal powder which melts at 260 C. While decomposing. The yield was about 50-70% of theoretical.

SODIUM N-METHYL-DIPROPARGYL-AMI-NO- METHANE .SULFONATE A suspension of 125 g. (1 mol) sodium N-methylaminomethane sulfonate in 750 'cc. methyl alcohol was put into the above-described reaction vessel and 238 g.

(2 mol) propargyl bromide was slowly dropped in the flask. In addition, suflicient hydrochloric acid in methyl alcohol was added to the reaction mixture to maintain the same during the reaction at a pH of 7. The reaction mass was left standing overnight and then filtered 01f.

5 The raw product was washed with a methyl alcohol-ether mixture and purified by dissolving the crystalline powder in a little water and precipitating with alcohol.

The end product are slightly. brownish flakes with a decomposition temperature of 324 C. The yield of pure 40 sodium N-methyl-dipropargyl-aminomethane sulfonate was about 30-40%.

The following examples illustrate electrolytic baths according to the invention:

Example I Nickel sulfate ....a.. g./liter 280 Nickel chloride do Boric acid. do u 40 Triethylpropargyl ammonium chloride do.. 0.08

50 Sodium benzaldehyde-o-sulfonate do 1.5 Temperature C pH 4.2

7 Current density ..amp./dm. 0.5-12

Example II 55 Nickel sulfate g /]iter 280 Nickel chlor do 40 Boric acid dn 40 Triethylpropargyl ammonium hydroxide do 0.05

p-Toluene sulfonam do 1 Temperature C 50 pH 4.6 Current density-.. amp./dm. 0.1-8

' Example 111 Nickel sulfate -g./1ite1. 280 Nickel chloride ...do 50 Boric'acid do 4O Trimethylpropargyl ammonium chloride do 0.02

Tolane disulfonic acid; do 0.02 Sodium benzaldehyde-o-sulfonate do 1 Benzene Slllfonamide do 0.4

. Temperature C..- 55 H 4.4

P Current densit y amp./dm. 0.1-10

Example IV Nickel sulfate g./liter 250 Nickel chlorid 100 Boric acid d0.. 40 Propargyl ammonium hydroxide do 0.03 Triethylpropargyl ammonium chloride do 0.02 Sodium benzaldehyde-o-sulfonatedo 1 Saccharine do 0.4 Temperature C 55 pH 4.2 Current density ..amp./dm. 0.1-

While the invention has been described hereinabove in connection with certain specific examples thereof, it Will be understood that many changes and modifications can be effected by the skilled in the art, particularly after benefiting from the present teaching, without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. In a bath for electro-depositing lustrous nickel and comprising an aqueous acidic solution of at least one nickel salt selected from the group consisting of nickel sulfate, nickel chloride, nickel fiuoborate and nickel sulfamate: a compound of the general formula wherein R R and R are members selected from the group consisting of hydrogen, alkyl and aryl radicals, R is an alkyne radical and X is a member selected from the group consisting of halogen and hydroxide, said compound being dissolved in the bath in a concentration of about 0.005 to 1 gram/liter.

2. The bath of claim 1, wherein from about 0.01 to 0.2 gram/liter of said compound is dissolved.

3. In a bath for electro-depositing lustrous nickel and comprising an aqueous acidic solution of at least one nickel salt selected from the group consisting of nickel sulfate, nickel chloride, nickel fluoborate and nickel sulfamate: trimethyl-propargyl-ammonium chloride dissolved in the bath in a concentration of about 0.005 to 1 gram/liter.

4. In a bath for electro-depositing lustrous nickel and comprising an aqueous acidic solution of at least one nickel salt selected from the group consisting of nickel sulfate, nickel chloride, nickel fluoborate and nickel sulfamate: tn'ethyl-propargyl-ammonium hydroxide dis- 6 solved in the bath in a concentration of about 0.005 to 1 gram/liter.

5. In a bath for electro-depositing lustrous nickel and comprising an aqueous acidic solution of at least one nickel salt selected from the group consisting of nickel sulfate, nickel chloride, nickel fluoborate and nickel sulfamate: phenyl-dimethyl-propargyl-ammonium chloride dissolved in the bath in a concentration of about 0.005 to l gram/liter.

6. In a bath for electro-depositing lustrous nickel and comprising an aqueous acidic solution of at least one nickel salt selected from the group consisting of nickel sulfate, nickel chloride, nickel fiuoborate and nickel sulfamate: propargyl-arnmonium hydroxide dissolved in the bath in a concentration of about 0.005 to 1 gram/liter.

7. In a bath for electro-depositing lustrous nickel and comprising an aqueous acidic solution of at least one nickel salt selected from the group consisting of nickel sulfate, nickel chloride, nickel fluoborate and nickel sulfamate: ethinyl-ammonium hydroxide dissolved in the bath in a concentration of about 0.005 to 1 gram/ liter.

8. Electrolyte composition for electrolytic deposition of lustrous nickel electrodeposits, said composition comprising an acid aqueous solution of a nickel salt, an organic sulfoxy compound serving as a brightening agent, said organic sulfoxy compound being selected from the group consisting of sulfonamides, sulfonimides and sulfonic acids, and a minor amount of the compound mam Br CHPCECH said minor amount being suflicient to produce lustrous nickel electrodeposits.

References Cited in the file of this patent UNITED STATES PATENTS 2,708,207 Girod May 10, 1955 2,712,522 Kardos et al. July 5, 1955 2,727,923 Husted Dec. 20, 1955 2,772,310 Morris Nov. 27, 1956 2,800,440 Brown July 23, 1957 2,800,442 Brown July 23, 1957 2,836,549 Nobel et al J May 27, 1958 2,905,602 Kirstahler et al. Sept. 22, 1959 

1. IN A BATH FOR ELECTRO-DEPOSITING LUSTROUS NICKEL AND COMPRISING AN AQUEOUS ACIDIC SOLUTION OF AT LEAST ONE NICKEL SALT SELECTED FROM THE GROUP CONSISTING OF NICKEL SULFATE, NICKEL CHLORIDE, NICKEL FLUOBORATE AND NICKEL SULFAMATE, A COMPOUND OF THE GENERAL FORMULA 